Compositions of various types have incorporated within them components which provide cooling sensation to skin. Such compositions include perfumes, lotions, shaving cream and gels, post-shaving preparations, shampoos, antiperspirants, deodorants, anti-acne medicines, first aid ointments, and a variety of other skin care and pharmaceutical products that are applied to the skin.
It is well established that the "cooling" effect of menthol is a physiological effect due to the direct action of menthol on the nerve endings of the human body responsive for the detection of hot or cold and is not due to latent heat of evaporation. It is believed that the menthol acts as a direct stimulus on the cold receptors at the nerve endings which in turn stimulate the central nervous system.
Although menthol is well established as a physiological coolant, its use and effectiveness is limited in some types of compositions by its strong minty odor and its relative volatility, particularly for perfumes, colognes, pre- or post-shave lotions, etc., where aroma is an important aesthetic attribute. The high volatility of menthol limits the period of time which it can provide cooling sensation. The high volatility of menthol can also result in eye sting for compositions applied to the face or in the vicinity of the eyes.
The cooling effect of menthol and other related terpene alcohols and their derivatives has also been studied and reported in Koryo, 95, (1970), pp. 39-43. 2,3-p-menthane diol has also been reported as having a sharp cooling taste (Beilstein, Handbuch der Organischen Cheme, 4th Ed. (1923) Vol. 6, p. 744).
Carboxamides have also been disclosed for use as coolants in a variety of compositions. Two patents describing such materials and compositions are U.S. Pat. No. 4,136,163, Jan. 23, 1979 to Watson et al. and U.S. Pat. No. 4,230,688, Oct. 28, 1980 to Rowsell et al. These patents as well as those set forth above are incorporated herein in their entirety by reference.
Ethanol and other volatile alcohols are commonly used in topical skin compositions to provide a coolant effect. The cooling sensation from volatile alcohols is due primarily to the latent heat of evaporation from the skin. After shave and pre-shave lotions typically contain high levels of ethanol, since it provides a cooling effect and does not interfere with the pleasing aroma typically associated with these products. Ethanol provides a strong initial cooling sensation, however cooling dissipates relatively rapidly as the ethanol evaporates. Unfortunately, the volatile alcohols also tend to impart a stinging sensation in addition to cooling, particularly with respect to skin that has been cut or recently shaved.
It is an object of this invention to provide improved coolant compositions for topical application to the skin.
In particular, it is an object of this invention to provide coolant compositions for application to the skin which can provide an improved cooling in combination with low sting to the skin and eyes.
It is a further object of this invention to provide coolant compositions, as described above, which can provide improved cooling over an extended period of time.
It is yet another object of this invention to provide such improved coolant compositions which need not contain aromatic ingredients, such as menthol, which can cause eye sting or adversely interfere with other fragrances incorporated into the composition.
The invention hereof, including its essential elements as well as a variety of additional ingredients, is described below. The compositions and method hereof can comprise, consist of, or consist essentially of the essential elements as well as any of the additional ingredients or limitations discussed herein.
All percentages reported herein are by weight of the total composition and all ratios are by weight unless otherwise specifically indicated.